ARPES data from VASP

[jmmshn]

I'm trying to generate some ARPES data using SumkDFTTools.spaghettis

I ran this example successfully but the resulting vasp.h5 does not have the data needed
https://triqs.github.io/dft_tools/latest/tutorials/nio_csc_vasp/nio.py.html#nio-py`

And it looks like this features is only supported for wannier and wien2k.

dft_tools/python/triqs_dft_tools/sumk_dft_tools.py

Lines 706 to 713 in 62ac241

	# initialisation
	if (proj_type != None):
	assert proj_type in ('wann', 'wien2k'), "'proj_type' must be either 'wann', 'wien2k'"
	if (proj_type != 'wann'):
	assert proj_type == self.dft_code, "proj_type must be from the corresponding dft inputs."
	things_to_read = ['n_k', 'n_orbitals', 'proj_mat', 'hopping']
	subgroup_present, values_not_read = self.read_input_from_hdf(
	subgrp=self.bands_data, things_to_read=things_to_read)

So I assume VASP + Wannier90 is OK here but I don't see an example run of this in the documentations. The closest thing I have found so far is this

https://github.com/TRIQS/solid_dmft/tree/87b7b89b2b1fb18b790c558ec6fd5df1bb5de55e/doc/debugging_examples/lno-csc-w90

But this looks like it's meant for 3.1.x. I'm wondering if anyone can point me in the right direction.

[the-hampel]

Hi @jmmshn ,

right now calculating the k-dependent spectral function with dft_tools works only for Wien2k and Elk. At least if you want to calculate it along high-symmetry lines. When using wannier90 (from any code) it works as well. See for example this tutorial when using wannier90: https://github.com/TRIQS/tutorials/blob/3.3.x/AbinitioDMFT/solutions/01s-solid_dmft.ipynb . However, this has some drawbacks, and only will work if you are not running CSC calculations as of now. If you do run CSC calculations you have to manually post-process some files. This is because in many cases you will have run disentanglement, and the disentanglement matrix cannot be obtained on a given k-path, only the final Wannier Hamiltonian H(R) can be FT to any H(k). But in general you can approximate things for post-processing by just using the Wannier Hamiltonian itself.

For VASP internal projectors I am currently working on storing the projectors along a specified k-path as well which will allow to plot spectral function along a path. But this is work in progress.

You can always get the spectral function on the regular k-mesh.

Best,
Alex

[jmmshn]

Thank you again for being so helpful!

disregard original message I read the tutorial more carefully and everything makes sense now.

[the-hampel]

Ah okay. Let me know if you have more questions. Let me say (regarding your original message) that in CSC the DFT calculated observables are only auxiliary and are not physical anymore, i.e. only the full DFT+DMFT lattice G(k,w) is meaningful. That said you still need to define the non-interacting part of that Green function, which is from Wannier90 or whatever way you use to construct the local orbitals. I will try to push on the VASP implementation but it will take a few more month probably.